AP - The Recognized Standard In Audio Test

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PDM-DRVR

Note: the PDM-DRVR accessory is intended for use with the APx PDM Option only

The AP PDM Line Driver solves a key problem encountered when testing PDM MEMS (Micro Electro-Mechanical Systems) microphones: the distance between the DUT and the analyzer itself.

PDM data is one-bit oversampled audio, most commonly employing a oversampling factor of 64. This means that in order to represent the performance of a PCM audio system with a 48kHz sample rate, many digital MEMS microphones employ a sample rate of 48kHz x 64 = 3.072MHz. The low-power, current-limited design of MEMS devices means that this high-frequency signal can suffer severe degradation due to cable capacitance in many test bench configurations, especially where the DUT must be a substantial distance - 1 meter or more - from the analyzer.

The Audio Precision PDM Line Driver provides a buffer for the PDM audio data, allowing cable lengths of up to 45ft (13.7m) to be used between DUT and analyzer with no loss or alteration of the digital signal.


PDM cables

The Audio Precision PDM Line Driver provides a buffer for the PDM audio data, allowing cable lengths of up to 45ft (13.7m) to be used between DUT and analyzer with no loss or alteration of the digital signal, as illustrated in the chart below.


Freq vs distance

 


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